# Copyright (c) 2011 Antoine d'Otreppe de Bouvette
# 
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
# 
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
# 
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
# IN THE SOFTWARE.

from functools import wraps

ENV_CLASS = 'Environment'

def loadEnvironment(package, module):
    try:
        pkgName = "%s.%s" % (package, module)
        mod = __import__(pkgName, globals(), locals(), ENV_CLASS)
        cls = getattr(mod, ENV_CLASS)
        
        return cls()
        
    except ImportError:
        # FIXME This can be inaccurate, if the env itself has an ImportError
        raise EnvironmentNotFoundError(package, module)

def singleton(func):
    @property
    @wraps(func)
    def newFunc(self):
        try:
            return func.__aspyct_injector_singleton
        except AttributeError:
            func.__aspyct_injector_singleton = val = func(self)
            return val

    return newFunc

def prototype(func):
    return property(func)

class EnvironmentNotFoundError(RuntimeError):
    def __init__(self, package, module):
        RuntimeError.__init__(self)
        self.package = package
        self.module = module

class AbstractEnvironmentError(RuntimeError):
    pass
